* Re: Consider for longterm kernels: mm: avoid swapping out with swappiness==0
2012-09-09 17:15 ` Rik van Riel
@ 2012-09-09 18:03 ` Shentino
2012-09-10 13:36 ` Cong Wang
2012-09-09 18:27 ` Ben Hutchings
2012-09-09 20:34 ` Willy Tarreau
2 siblings, 1 reply; 8+ messages in thread
From: Shentino @ 2012-09-09 18:03 UTC (permalink / raw)
To: Rik van Riel
Cc: Ben Hutchings, Andrew Morton, Greg Kroah-Hartman, stable,
Zdenek Kaspar, linux-mm
On Sun, Sep 9, 2012 at 10:15 AM, Rik van Riel <riel@redhat.com> wrote:
> On 09/09/2012 12:57 PM, Ben Hutchings wrote:
>>
>> On Sat, 2012-08-25 at 16:56 +0200, Zdenek Kaspar wrote:
>>>
>>> Hi Greg,
>>>
>>>
>>> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=fe35004fbf9eaf67482b074a2e032abb9c89b1dd
>>>
>>> In short: this patch seems beneficial for users trying to avoid memory
>>> swapping at all costs but they want to keep swap for emergency reasons.
>>>
>>> More details: https://lkml.org/lkml/2012/3/2/320
>>>
>>> Its included in 3.5, so could this be considered for -longterm kernels ?
>>
>>
>> Andrew, Rik, does this seem appropriate for longterm?
>
>
> Yes, absolutely. Default behaviour is not changed at all, and
> the patch makes swappiness=0 do what people seem to expect it
> to do.
Just curious, but what theoretically would happen if someone were to
want to set swappiness to 200 or something?
Should it be sorta like vfs_cache_pressure?
> --
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: Consider for longterm kernels: mm: avoid swapping out with swappiness==0
2012-09-09 18:03 ` Shentino
@ 2012-09-10 13:36 ` Cong Wang
2012-09-10 17:07 ` Shentino
0 siblings, 1 reply; 8+ messages in thread
From: Cong Wang @ 2012-09-10 13:36 UTC (permalink / raw)
To: linux-mm; +Cc: stable
On Sun, 09 Sep 2012 at 18:03 GMT, Shentino <shentino@gmail.com> wrote:
>
> Just curious, but what theoretically would happen if someone were to
> want to set swappiness to 200 or something?
>
> Should it be sorta like vfs_cache_pressure?
>
How could it be set to 200? As 0~100 is valid:
{
.procname = "swappiness",
.data = &vm_swappiness,
.maxlen = sizeof(vm_swappiness),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &one_hundred,
},
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^ permalink raw reply [flat|nested] 8+ messages in thread* Re: Consider for longterm kernels: mm: avoid swapping out with swappiness==0
2012-09-10 13:36 ` Cong Wang
@ 2012-09-10 17:07 ` Shentino
2012-09-10 17:40 ` Shentino
0 siblings, 1 reply; 8+ messages in thread
From: Shentino @ 2012-09-10 17:07 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-mm, stable
On Mon, Sep 10, 2012 at 6:36 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Sun, 09 Sep 2012 at 18:03 GMT, Shentino <shentino@gmail.com> wrote:
>>
>> Just curious, but what theoretically would happen if someone were to
>> want to set swappiness to 200 or something?
>>
>> Should it be sorta like vfs_cache_pressure?
>>
>
>
> How could it be set to 200? As 0~100 is valid:
>
> {
> .procname = "swappiness",
> .data = &vm_swappiness,
> .maxlen = sizeof(vm_swappiness),
> .mode = 0644,
> .proc_handler = proc_dointvec_minmax,
> .extra1 = &zero,
> .extra2 = &one_hundred,
> },
My comment/question was more abstract and focusing on the comparison
to vfs_cache_pressure.
:P
>
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^ permalink raw reply [flat|nested] 8+ messages in thread* Re: Consider for longterm kernels: mm: avoid swapping out with swappiness==0
2012-09-10 17:07 ` Shentino
@ 2012-09-10 17:40 ` Shentino
0 siblings, 0 replies; 8+ messages in thread
From: Shentino @ 2012-09-10 17:40 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-mm, stable
On Mon, Sep 10, 2012 at 10:07 AM, Shentino <shentino@gmail.com> wrote:
> On Mon, Sep 10, 2012 at 6:36 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> On Sun, 09 Sep 2012 at 18:03 GMT, Shentino <shentino@gmail.com> wrote:
>>>
>>> Just curious, but what theoretically would happen if someone were to
>>> want to set swappiness to 200 or something?
>>>
>>> Should it be sorta like vfs_cache_pressure?
>>>
>>
>>
>> How could it be set to 200? As 0~100 is valid:
>>
>> {
>> .procname = "swappiness",
>> .data = &vm_swappiness,
>> .maxlen = sizeof(vm_swappiness),
>> .mode = 0644,
>> .proc_handler = proc_dointvec_minmax,
>> .extra1 = &zero,
>> .extra2 = &one_hundred,
>> },
>
> My comment/question was more abstract and focusing on the comparison
> to vfs_cache_pressure.
Just to be clear about what I meant.
Both swapping and reclaiming from dentry/inode caches both share the
common factor of being alternatives to reclaiming from page cache when
memory is tight.
So I was wondering how similiar in effect these two knobs should be.
One possible use case off the top of my head is a file server that
banks heavily on page cache and spends most of its runtime sending
file data over the network. It might be overkill but swappiness > 100
might actually be beneficial here. I have no numbers to back it up
though as it's a rough idea.
Sorry if I'm butting in on the subject but I was curious about the idea.
Also still learning how to pos tin general on the kernel lists, so
apologies if I've been rude or anything.
>
> :P
>>
>> --
>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: Consider for longterm kernels: mm: avoid swapping out with swappiness==0
2012-09-09 17:15 ` Rik van Riel
2012-09-09 18:03 ` Shentino
@ 2012-09-09 18:27 ` Ben Hutchings
2012-09-09 20:34 ` Willy Tarreau
2 siblings, 0 replies; 8+ messages in thread
From: Ben Hutchings @ 2012-09-09 18:27 UTC (permalink / raw)
To: Rik van Riel
Cc: Andrew Morton, Greg Kroah-Hartman, stable, Zdenek Kaspar,
linux-mm
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On Sun, 2012-09-09 at 13:15 -0400, Rik van Riel wrote:
> On 09/09/2012 12:57 PM, Ben Hutchings wrote:
> > On Sat, 2012-08-25 at 16:56 +0200, Zdenek Kaspar wrote:
> >> Hi Greg,
> >>
> >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=fe35004fbf9eaf67482b074a2e032abb9c89b1dd
> >>
> >> In short: this patch seems beneficial for users trying to avoid memory
> >> swapping at all costs but they want to keep swap for emergency reasons.
> >>
> >> More details: https://lkml.org/lkml/2012/3/2/320
> >>
> >> Its included in 3.5, so could this be considered for -longterm kernels ?
> >
> > Andrew, Rik, does this seem appropriate for longterm?
>
> Yes, absolutely. Default behaviour is not changed at all, and
> the patch makes swappiness=0 do what people seem to expect it
> to do.
OK, I've queued this up for 3.2.
Ben.
--
Ben Hutchings
Time is nature's way of making sure that everything doesn't happen at once.
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: Consider for longterm kernels: mm: avoid swapping out with swappiness==0
2012-09-09 17:15 ` Rik van Riel
2012-09-09 18:03 ` Shentino
2012-09-09 18:27 ` Ben Hutchings
@ 2012-09-09 20:34 ` Willy Tarreau
2 siblings, 0 replies; 8+ messages in thread
From: Willy Tarreau @ 2012-09-09 20:34 UTC (permalink / raw)
To: Rik van Riel
Cc: Ben Hutchings, Andrew Morton, Greg Kroah-Hartman, stable,
Zdenek Kaspar, linux-mm
On Sun, Sep 09, 2012 at 01:15:59PM -0400, Rik van Riel wrote:
> >>http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=fe35004fbf9eaf67482b074a2e032abb9c89b1dd
> >>
> >>In short: this patch seems beneficial for users trying to avoid memory
> >>swapping at all costs but they want to keep swap for emergency reasons.
> >>
> >>More details: https://lkml.org/lkml/2012/3/2/320
> >>
> >>Its included in 3.5, so could this be considered for -longterm kernels ?
> >
> >Andrew, Rik, does this seem appropriate for longterm?
>
> Yes, absolutely. Default behaviour is not changed at all, and
> the patch makes swappiness=0 do what people seem to expect it
> to do.
Just for the record, in 3.0 and below we don't have vmscan_swappiness(),
so if the match makes sense there, that function will need to be backported,
in which mem_cgroup_swappiness() will have to be replaced by get_swappiness().
Regards,
Willy
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^ permalink raw reply [flat|nested] 8+ messages in thread